In general REBT is arguably one of the most investigated theories in the field of psychotherapy and a large amount of clinical experience and a substantial body of modern psychological research have validated and substantiated many of REBTs theoretical assumptions on personality and psychotherapy.

His stuff works. And it's as simple as ABCD — quite literally, as you'll see below.

So how can you never be frustrated again? Let's break it down.

The tyranny of 'should'

Let's cut to the chase, shall we? Here's what you need to take away from Ellis' work:

You don't get frustrated because of events. You get frustrated because of your beliefs.

And where did this idea start? Ancient philosophy. Stoicism. That's where Ellis found the concept. And then he proved it really worked.

... if you understand how you upset yourself by slipping into irrational shoulds, oughts, demands, and commands, unconsciously sneaking them into your thinking, you can just about always stop disturbing yourself about anything.

You're stuck in traffic and that makes you angry, right? Wrong.

Kevork Djansezian/Getty

Traffic happens. But you think it shouldn't happen to you. And the thing that's making you miserable is that word "should."

Here's an example. I say, "This headache remedy probably won't work but give it a shot." So you try it. And it doesn't work. You're not frustrated.

Okay, same situation but I say, "This always works." It fails. Now you're annoyed. What changed? Your expectation.

Or you tell a five-year old to stop yelling. They don't listen. You don't get that bothered. After all, the kid is five.

But if you tell me to stop yelling and I don't listen, you get angry. What's different? "Eric should stop. He's an adult."

Again, nothing changed but your belief.

Pretty straightforward, right? But that leads to a question: how do you change your beliefs? Ellis has an answer.

(For more on a fun way to be happier and more successful, click here.)

The universe is not taking orders from you. (Sorry)

It's as simple as ABCD. Really.

A is adversity. Traffic is awful.

B is your beliefs. And often they're irrational. "This shouldn't happen to me." Well, guess what, Bubba? It is happening.

C is consequences. You get angry, frustrated or depressed.

In very few cases can you change A. But you can change B. And that will change C. So let's bring in the 4th letter.

D: Dispute your irrational beliefs. "Wait a second. When did the universe guarantee me a trouble-free existence? It didn't. Traffic has happened before. It will happen again. And I will survive."

"I would very much like or prefer to have success, approval, or comfort," and then end with the conclusion, "But I don't have to have it. I won't die without it. And I could be happy (though not as happy) without it."

But you can't demand the universe bend to your will. That's where the frustration and anger creep in — because that godlike insistence isn't rational.

When you insist, however, that you always must have or do something, you often think in this way: "Because I would very much like or prefer to have success, approval, or pleasure, I absolutely, under practically all conditions, must have it. And if I don't get it, as I completely must, it's awful, I can't stand it, I am an inferior person for not arranging to get it, and the world is a horrible place for not giving me what I must have! I am sure that I'll never get it, and therefore I can't be happy at all!"

When you're angry, frustrated or depressed look for those irrational beliefs.

"People should treat me kindly and fairly all the time." Sound rational? Hardly.

"I ought to succeed at this. If I don't, I'm a failure and a loser." Really?

What were you anxious or overconcerned about? Meeting new people? Doing well at work? Winning the approval of a person you liked? Passing a test or a course? Doing well at a job interview? Winning a game of tennis or chess? Getting into a good school? Learning that you have a serious disease? Being treated unfairly? Look for your command or demand for success or approval that was creating your anxiety or overconcern. What was your should, ought, or must?

But when you start disputing you'll see that your expectations aren't in line with reality. And with a little work, those expectations will start to change.

(For more happiness lifehacks you can learn from ancient philosophy, click here.)

Sum up

It's as simple as ABCD. Next time you're turning red and clenching your fists, give this a shot:

A is Adversity. Like traffic. Sorry, no genie can let you wish it away.

B is Beliefs. Look for beliefs with these troublesome words: should, ought and must. "Traffic shouldn't be this bad." Not rational. Traffic is what it is. Sorry.

C is Consequences. You banging the steering wheel with your fist and sending your blood pressure into the stratosphere.

D is Dispute. Are you demanding the universe and everyone bend to your wishes? Is that rational? No way. You can want, you can wish and you can definitely try your best in the future, but you cannot demand if you want to stay happy and sane.

Life is not perfect. People aren't perfect. You, dear reader, are not perfect. And that's okay. But having beliefs that any of these things "should" be the way you want causes you a lot of unnecessary suffering.

Many of your irrational beliefs are not immediately obvious. Sometimes you'll have to dig to find them. And you'll need to dispute them a fair amount before new reasonable beliefs kick in. But you can definitely make progress.

What did Epictetus, the great Stoic philosopher, say way back in the first century AD?

People are disturbed not by things, but by the views they take of them.